Golden rice

From Academic Kids

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GoldenRice-WhiteRice.jpg
White rice and golden rice

Golden rice is a strain of rice (Oryza sativa) produced through genetic engineering, the scientific details of the rice were first published in Science in 2000Template:Ref. The rice has been modified to produce enzymes for the biosynthesis of beta-carotene in the endosperm, and was developed as a fortified food to be used in areas where there is a shortage of dietary Vitamin A. The research was largely funded by the Rockefeller Foundation.

In 2005, a new strain called "golden rice 2" was announced, with up to 23 times more beta-caroteneTemplate:Ref. Neither variety are available for human consumption.

Contents

Creation of golden rice

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Carotenoid.PNG
A simplified overview of the carotenoid biosynthesis pathway. The enzymes expressed in the endosperm of golden rice, shown in red, catalyze the biosyntheis of beta-carotene from geranylgernayl-diphosphate. Beta-carotene is believed to be converted to retinal and subsequently retinol (vitamin A) in the animal gut

Golden rice was created by Ingo Potrykus of the Institute of Plant Sciences at the Swiss Federal Institute of Technology, working with Peter Beyer of the University of Freiburg

Golden rice was designed to produce Vitamin A precursor beta-carotene in the part of rice that people eat, the endosperm. The rice plant can produce beta-carotene, it is a carotenoid that occurs in the leaves and is involoved in photosynthesis, however the plant does not normally produce the pigment in the endosperm since the endosperm is not a tissue where photosynthesis takes place.

Golden rice was created by engineering rice with three beta-carotene biosynthesis genes:

  1. psy (photoene synthase)
  2. lyc (lycopene cyclase) both from daffodil (Narcissus pseudonarcissus), and
  3. ctr1 from the soil bacterium Erwinia uredovora

The psy, lyc and ctr1 genes were transformed into the nuclear genome and placed under the control of an endosperm specific promoter, so that they are only expressed in the endosperm. The lyc gene transfomed into the rice has a transit peptide sequence attached so that it is targeted to the plastid where geranylgeranyl-diphosphate formation occurs. It was important to use the bacterial gene ctr1 since it can catalyze multiple steps in the synthesis of carotenoids, these steps require more than one enzyme in plantsTemplate:Note.

The resulting plants produce significant amounts of beta-carotene in the endosperm, giving the rice a distinctive yellow colour. At the time of publication Golden rice was considered a significant breakthrough in biotechnology as the researchers had engineered an entire biosynthetic pathway.

Golden rice has been bred with local rice cultivars in the Philippines, Taiwan and with the American rice variety Cocodrie, the first field trials of these golden rice cultivars were conducted by Louisiana State University AgCenter in 2004 Template:Ref. Field testing will allow more accurate measurment of the nutritional value of golden rice and will enable feeding tests to be performed.

Golden rice 2

In 2005 a team of Reseachers at biotechnology company Syngenta produced a variety of golden rice called golden rice 2. They combined a photoene synthase gene from maize with the lyc and ctr1 from the original golden rice. Golden rice 2, produces 23 times more carotenoids than golden rice (up to 37µg/g), and preferentially accumulates beta-carotene.

Vitamin A deficiency

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TIME_cover_july_31_2000.jpg
Golden rice and co-creator Professor Ingo Potrykus on the cover of TIME magazine, July 2000

The research that led to golden rice was conducted with the goal of helping the millions of children who suffer from Vitamin A deficiency (VAD). At the beginning of the 21st century, 124 million people were estimated to be affected by VAD, people are affected in 118 counrties in Africa and South East Asia. VAD is responsible for 1-2 million deaths, 500,000 cases of irreversible blindness and millions of cases of xerophthalmia annuallyTemplate:Ref. Children and pregnant women are at highest risk. Vitamin A is supplemented orally and by injection in areas where the diet is deficient in Vitamin A.

Because many children in countries where there is a dietary deficiency in Vitamin A rely on rice as a staple food, the genetic modification to make rice produce provitamin A (beta-carotene) is seen a simple and less expensive alternative to vitamin supplements or an increase in the consumption of green vegetables or animal products. It is the genetically engineered equivalent of fluoridated water or iodized salt.

A theorhetical analysis of the potential nutritional bebefits of golden rice, show that consumption of golden rice would not eliminate the problems of blindness and increased mortality, but should be seen as a complement to other methods of Vitamin A supplementationTemplate:Ref. Golden rice and Golen rice 2 have not undergone nutritional testing.

Golden rice and intellectual property issues

Potrykus has spearheaded an effort to have golden rice distributed for free to subsistence farmers; this required several companies which had Intellectual Property rights to the results of Beyer's research to license it for free. Beyer had received funding from the European Commissions 'Carotene Plus' research program, by accepting those funds he was required by law to give the rights to his discovery to the corporate sponsors of that program, Zeneca, now Syngenta. Beyer and Poyrykus has used 70 Intellectual Property rights belonging to 32 different companies and universities in the making of golden rice, they needed to establish free licences for all of these so that Syngenta and humanitarian partners in the project could use golden rice in breeding programs and to develop new cropsTemplate:Ref.

Free licences were granted quickly due to the positive publication that golden rice received; it was the first genetically modified crop that was inarguably beneficial, and thus met with widespread approval. Monsanto was one of the first companies to grant the group free licences.

The group also had to define the cutoff between humanitarian and commercial use, this figure was set at USD$10 000, therefore as long as a farmer or subsequent user of golden rice genetics does not make more than $10 000, then no royalties need to be paid to Syngenta for commercial use.

Objections

Greenpeace pointed out that the amount of Vitamin A in golden rice (1.6 micrograms of beta-carotene per gram of rice) was too low: a person would have to eat 1.5–2 kg of the rice per day to get the recommended daily allowance of provitamin A. However, the new strain of "golden rice 2" contains up to 37 micrograms per gram of rice, which may address this objection. However, Greenpeace opposes any genetically modified organisms (GMOs), and is concerned that golden rice is a Trojan horse that will "open the door" to more widespread use of GMOsTemplate:Ref.

Vandana ShivaTemplate:Ref, an Indian anti-GMO activist, argued that the problem was not particular deficiencies in the crops themselves, but problems with poverty and loss of biodiversity in food crops. These problems are aggravated by the corporate control of agriculture based on genetically modified foods. By focusing on a narrow problem (vitamin A deficiency), Shiva argued, the golden rice proponents were obscuring the larger issue of a lack of broad availability of diverse and nutritionally adequate sources of food. Similarly other groups have argued that a varied diet containing vitamin A rich foods like sweet potato, leafy green vegetables and fruit would provide children with sufficient vitamin ATemplate:Ref. While this is true, a varied diet is beyond the means of the many of the poor, that is why they subsist on a diet of rice.

Many cultures base the quality of rice on its whiteness. In spite of the touted health benefits, due to the yellow coloring of golden rice, recipients may not be easily convinced it is healthier.

References

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